It seems it’s related to AssetDatabase v2. I think you have at least two options you can try:
- Delete the project “Library” folder, which forces Unity to reimport everything and perhaps does not run into the compatibility issue then.
- By-pass the new system as mentioned here .
If the error can be still reproduced after step 1., I think it would be helpful to submit a bug-report as described in this document:
If you don’t do it, it might be a long time until someone else reports them or until Unity Technologies find them. Please post the Case number (number only, not the link) in this forum thread for Unity staff to pick up.